Motorcycle engines are well known that may include chain-driven camshafts. There may be more than one chain involved, with one chain driving one of the camshafts, and another chain driving a second camshaft off of the first camshaft.
The chain drives the various camshafts by being wrapped around sprockets on ends of the shafts. There is typically some degree of slack present in the chain if no additional tensioner is present. Any slack is undesirable because it can cause a deviation from correct cam timing, as well as producing noise from less of control of the valve or valve spring, or slapping of the chain. Therefore, it is desirable to provide a steady, even tension on the chain so that slack between the sprockets is reduced or eliminated to a desirable degree.